Briquet packing density

ABSTRACT

Modified charcoal briquets having a pillow silhouette when viewed from at least one side and configured to have less volume than similar unmodified pillow shaped briquets having the same dimensions are described. A random packing density for the modified briquets is between about 0.70 times and 0.92 times a random packing density for the unmodified pillow shape briquets. The random packing density for the modified briquets is between about 35% and 46%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of pending U.S. application Ser. No. 29/208,910 filed Jul. 7, 2004, which is incorporated herein.

FIELD OF THE INVENTION

This invention relates to the field of charcoal briquets and other solid fuel compositions.

BACKGROUND OF THE INVENTION

There is great consumer interest in using charcoal for outdoor cooking in which meals can be prepared and served quickly for individual or large group consumption. Consumers desire cooking and grilling with charcoal briquets that are easily stackable to form the traditional starter pile, easily ignitable, maintain a uniform and efficient combustion that ignites the individual briquets in the starter pile, and have a sufficiently long burn period. Similarly, consumers desire to handle dirty charcoal as little as possible when forming traditional starter piles and the like.

Charcoal briquettes are often configured in a generally pillow-shape. This configuration provides for both reasonable ease of manufacturing by the supplier, and handling by the consumer. Pillow-shaped briquets are typically used for cooking on a grill or the like by pouring a multiplicity of briquets from a bag onto a grill to form a mounded or conical configuration or stack, adding lighter fluid, followed by igniting the mound of briquets with an ignition source.

An “ignition phase” follows as burning proceeds from the surface of the briquet. A gray ash is formed on a significant portion of each briquet until a majority of the exposed surfaces have ignited, and burning has progressed inwardly toward the intended area of the briquet. Thus, completion of the ignition phase is identified by the formation of visible ash on the briquet.

At this point, the briquets are spread out under a grill or the like, and they continue to burn with intense heat suitable for cooking and grilling throughout a “bum phase”. For maximum performance of the briquets, it is desirable that the ignition phase be limited in time so that the briquets may be used for cooking or grilling without undue delay, such that the duration of the burn phase is optimized and extended to provide adequate cooking or grilling time as desired by the consumer. After the briquets are burned thoroughly, ash remains.

There has been some previous work in the ornamental and geometrical configuration of charcoal briquets. For example, U.S. Des. 389,453 to Mitchell et al. describes a charcoal briquet having a groove generally in the shape of the letter “K”, and U.S. Pat. No. 4,496,366 to Peters describes charcoal having a briquet, or other geometric configuration, purportedly to achieve desired lighting and burn characteristics. In another example, U.S. Pat. No. 6,074,446 to Fujino describes charcoal having a plurality of air passing portions or grooves in its body purportedly to supply combustion air inside the charcoal body while burning.

However, previously known ornamental and geometrically configured charcoal briquets fail to address enhancing the surface of pillow-shaped briquets to improve packing density, and the random, non-mating stacking ability properties of the briquets, as well as to improve ignition and burn phase characteristics. Particularly charcoal briquets used for home grilling and cooking, wherein the consumer desires charcoal briquets that require less handling, and that can be readily ignited to provide maximum heat initially, followed by an improved burn phase.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved modified charcoal briquet having a pillow silhouette when viewed from at least one side and configured to have less volume than a similar unmodified pillow briquets having the same dimensions.

The modified pillow shaped charcoal briquets of the present invention have a random packing density between about 0.70 times and 0.92 times a random packing density for the unmodified pillow briquets. Preferably, the random packing density for the modified briquet is between about 35% and 46%.

Modified pillow shaped charcoal briquets of the present invention having these improved random packing density characteristics have enhanced ignition and burn phase-properties, when compared to unmodified briquets having a pillow silhouette when viewed from at least one side.

These and other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments of the invention, taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention, and wherein:

FIG. 1A is a top plan view of a generalized pillow shaped charcoal briquet;

FIG. 1B is a side view of the generalized pillow shaped briquet of FIG. 1A taken along the direction of “B”;

FIG. 1C is a side view of the generalized pillow shaped briquet of FIG. 1A taken along the direction of “C”;

FIG. 1D is a silhouette of the generalized pillow shaped briquet of FIG. 1A taken along the direction of “D”;

FIG. 1E is a silhouette of the generalized pillow shaped briquet of FIG. 1A taken along the direction of “C”;

FIG. 2A is a top plan view of a less generalized pillow shaped charcoal briquet;

FIG. 2B is a side view of the less generalized pillow shaped briquet of FIG. 2A taken along the direction of “B”;

FIG. 2C is a side view of the less generalized pillow shaped briquet of FIG. 2A taken along the direction of “C”;

FIG. 2D is a silhouette of the less generalized pillow shaped briquet of FIG. 2A taken along the direction of “D”;

FIGS. 3A and 3B depict examples of Boolean difference operations;

FIG. 4 depicts an example of a Boolean union operation;

FIG. 5A is a top plan view of a modified pillow shaped charcoal briquet embodying the present invention;

FIG. 5B is a silhouette of the modified pillow shaped charcoal briquet in FIG. 5A;

FIG. 6A is a top plan view an another embodiment of the modified pillow shaped charcoal briquet according the present invention;

FIG. 6B is a silhouette of the modified pillow shaped charcoal briquet in FIG. 6A;

FIG. 7A is a top plan view an another embodiment of the modified pillow shaped charcoal briquet according the present invention;

FIG. 7B is a silhouette of the modified pillow shaped charcoal briquet in FIG. 7A taken along the direction of “B”;

FIG. 7C is a silhouette of the modified pillow shaped charcoal briquet in FIG. 7A taken along the direction of “C”;

FIG. 7D is a silhouette of the modified pillow shaped charcoal briquet in FIG. 7A;

FIG. 8A is a top plan view an another embodiment of the modified pillow shaped charcoal briquet according the present invention;

FIG. 8B is a silhouette of the modified pillow shaped charcoal briquet in FIG. 8A taken along the direction of “B”;

FIG. 8C is a silhouette of the modified pillow shaped charcoal briquet in FIG. 8A taken along the direction of “C”;

FIG. 8F is a cross section of the modified pillow shaped charcoal briquet in FIG. 8A taken along the direction of “F-F”;

FIG. 9A is a top plan view an another embodiment of the modified pillow shaped charcoal briquet according the present invention;

FIG. 9B is a side view of the modified pillow shaped charcoal briquet in FIG. 9A taken along the direction of “B”;

FIG. 9C is a side view of the modified pillow shaped charcoal briquet in FIG. 9A taken along the direction of “C”;

FIG. 10A is a top plan view an another embodiment of the modified pillow shaped charcoal briquet according the present invention; and

FIG. 10B is a silhouette of the modified pillow shaped charcoal briquet in FIG. 10A taken along the direction of either “B” or “C”.

Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate preferred embodiments of the invention, in one form, and such examples are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION

The embodiments are illustrated in the context of charcoal briquets for consumer use. The skilled artisan will readily appreciate, however, that the materials and methods disclosed herein have application in a number of other contexts where solid fuel is used, particularly where low weight and high performance are important.

The shape of the pillow briquet is well known. Various views of a generalized pillow shape 100 as can be used for a briquet are shown in FIGS. 1A-1E. FIG. 1A shows a plan view 110 and a periphery 117 of the generalized pillow shape. The periphery 117 can be described by the following equation of a superellipse: $\begin{matrix} {{{\frac{x}{a}}^{2/n} + {\frac{y}{b}}^{2/n}} = 1} & \left( {{Equation}\quad 1} \right) \end{matrix}$ where 0<n<1. As n approaches 0, corners 115 of the periphery 117 become more close to orthogonal. As n approaches 1, the corners 115 of the periphery 117 become more rounded. The periphery 117 becomes an ellipse when n=1. Any periphery described by Equation (1) can be suitable for a pillow briquet. The periphery 117 can also be characterized by lengths S₁ and S₂ of two sides. In FIG. 1A, S₁≠S₂, the periphery 117 is not equiaxed, and the briquet 100 has a somewhat rectangular shape, as shown.

FIG. 1B shows a side view of the generalized pillow briquet 100 as viewed along the direction B in FIG. 1A. The maximum width of the briquet 100 in this view is S₁. A line 145 is indicated at the maximum width S₁. The line 145 separates the briquet 100 into a first portion 140 and a second portion 150. The first portion 140 of the briquet 100 is convex with a maximum height h₁. The second portion 150 of the briquet 100 is convex with a maximum height h₂. In FIG. 1B, h₁≠h₂, and the first portion 140 and the second portion 150 have different curvatures and volumes, as shown.

FIG. 1C shows a side view of the generalized pillow briquet 100 as viewed along the direction C in FIG. 1A. The maximum width of the briquet 100 in this view is S₂. The line 145 in FIG. 1B continues along the maximum width S₂ in FIG. 1C. As before, the line 145 separates the briquet 100 into the first portion 140 and the second portion 150. The first portion 140 of the briquet 100 is convex with a maximum height h₁. The second portion 150 of the briquet 100 is convex with a maximum height h₂, different from h₁. As discussed above, the first portion 140 and the second portion 150 have different curvatures and volumes. The briquet 100 is not symmetric with respect to the line 145.

A silhouette is an outline of a solid object as cast by its shadow. FIG. 1D can be described as a silhouette 120 of the pillow briquet 100 as viewed along direction B in FIG. 1A. FIG. 1D can be described also as a cross section of the pillow briquet 100 as taken through the line D-D in FIG. 1A. Similarly, FIG. 1E can be described as a silhouette 130 of the pillow briquet 100 as viewed along direction C in FIG. 1A.

FIGS. 2A-2D illustrate a less generalized pillow briquet 200 than is shown in FIG. 1A-1E. The briquet 200 has a pillow shape as is commonly used in the industry. FIG. 2A shows a plan view 210 and a periphery 217 of the pillow briquet 200. The periphery 217 can be described by Equation (1) in the special case where a a=b: $\begin{matrix} {{{\frac{x}{a}}^{2/n} + {\frac{y}{a}}^{2/n}} = 1} & \left( {{Equation}\quad 2} \right) \end{matrix}$ where 0<n<1. As n approaches 0, corners 215 of the periphery 217 become closer to orthogonal. As n approaches 1, the corners 215 of the periphery 217 become more rounded. The periphery becomes a circle when n=1. Any periphery described by Equation (2) can be suitable for a pillow briquet. The periphery 217 can also be characterized by the lengths S₁ and S₂ of the two sides. In FIG. 2A, S₁=S₂, the periphery 217 is equiaxed and the briquet 200 has a somewhat square shape as shown.

FIG. 2B shows a side view of the pillow briquet 200 as viewed along the direction B in FIG. 2A. The maximum width of the briquet 200 in this view is S₁. A line 245 is indicated at the maximum width S₁. The line 245 separates the briquet 200 into a first portion 240 and a second portion 250. The first portion 240 of the briquet 200 is convex with a maximum height h₁. The second portion 250 of the briquet 200 is convex with a maximum height h₂. In FIG. 2B, h₁=h₂, and the first portion 240 and the second portion 250 have the same curvatures and volumes as shown. The line 245 is also the midline of the briquet 200.

FIG. 2C shows a side view of the generalized pillow briquet 200 as viewed along the direction C in FIG. 2A. As S₁=S₂, FIG. 2C is the same as FIG. 2B. The briquet 200 is symmetric with respect to the line 245.

FIG. 2D can be described as a silhouette 220 of the pillow briquet 200 as viewed along either direction B or direction C in FIG. 2A. FIG. 2D can be described also as a cross section of the pillow briquet 200 as taken through the line D-D in FIG. 2A.

Packing density is defined as the fraction of a volume filled by a given collection of solids. The maximum packing density of spheres is 74.0%, which is achieved in cubic or hexagonal close packing arrangements. Spheres arranged randomly, for example, tossed into a container and then shaken, have a random packing density of only about 64%, which is significantly smaller than their maximum, ordered, packing density.

Packing densities can also be found for non-spherically shaped solids. In 2004, Chaikin showed that a random packing of about 125 pounds of M&M's® chocolate candies (oblate spheroids) has a random packing density of about 68%, or 4% greater than for spheres (Princeton University Press Release, Feb. 12, 2004).

The packing density of pillow-shaped briquets has been found to be about 50%. The packing density, of course, depends on the exact shape of the briquets. Pillow-shaped briquets are made by several manufacturers; dimensions S₁, S₂, h₁, h₂, as discussed above in FIGS. 1 and 2, can have a wide range of values.

It has been found that by making small modifications to the form of pillow-shaped briquets, while still retaining the overall pillow shape and dimensions, the packing density of the briquets is reduced and several advantages are realized.

In Boolean geometry, multiple solid objects can be combined using Boolean geometric operations. Common operations include “union” (addition) and “difference” (subtraction) operations. Union operations combine two or more shapes. Difference operations can be used to cut one shape out of another.

Examples of Boolean difference operations are shown in FIGS. 3A and 3B. In FIG. 3A, a solid cube 310 has a centerline 320. A solid cylinder 330 has a centerline 340. The cylinder 330 is subtracted from the cube 310 in an orientation where the cube centerline 320 and the cylinder centerline 340 are superimposed. The resulting shape 350 is a cube with a cylindrical bore 360 around the centerline 320.

In FIG. 3B, the solid cube 310 also has an edge 315. The cylinder 330 is subtracted from the cube 310 in a different orientation. The centerline 340 of the cylinder 330 is aligned with the edge 315 of the cube 310 before the difference operation is performed. The resulting shape 370 is a cube with a partial cylinder piece cut out along one of the edges (the former edge 315). A volume corresponding to the entire cylinder 330 volume need not be removed from the cube 310 to be a Boolean difference operation.

An example of a Boolean union operation is shown in FIG. 4. A solid cube 410 has a centerline 420, a top face 422, and a bottom face 424. A solid cylinder 430 has a centerline 440. The cylinder 430 is combined with or added to the cube 410 in an orientation where the cube centerline 420 and the cylinder centerline 440 are superimposed. The resulting shape 450 is a cube with a portion 432 of the cylinder 430 protruding above the top face 422 and another portion 434 of the cylinder 430 protruding below the bottom face 424, both portions 432, 434 along the centerlines 420, 440.

Small modifications to the form of pillow-shaped briquets can be made using Boolean geometric operations, while still retaining the overall pillow shape and dimensions. In some embodiments, the packing density of the modified briquets is less than the packing density of the briquets before modification (the unmodified briquets).

FIG. 5A shows a plan view of a modified pillow briquet 500 according to an embodiment of the invention. The briquet 500 has been modified by a Boolean difference operation. The dotted regions indicate a volume 512, consisting of two partial toruses, which is missing from the briquet 500 on the face 510 shown in FIG. 5A.

In the example in FIG. 5A, the Boolean operation is performed on only one face, the face 510. FIG. 5B shows a silhouette 520 of the modified briquet 500 as viewed from the side along either the B or C directions in FIG. 5A. The silhouette 520 has the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. Thus, the modified briquet 500 has a pillow silhouette when viewed from at least one side. In some arrangements, both faces of a briquet, such as the briquet 500, can be modified in the same way. In some arrangements, the Boolean operation performed on each face is the same. In other arrangements, the Boolean operation performed on each face is different.

The briquet 500 shown in FIGS. 5A and 5B has a somewhat square periphery before modification and is symmetric about its midline as discussed above for the unmodified briquet 200 in FIGS. 2B and 2C. In other arrangements, the briquet 500 can have a circular, elliptical, or somewhat rectangular periphery before modification. In other arrangements, the briquet 500 can be asymmetric about its line of maximum width before modification, as discussed above for the unmodified briquet 100 in FIGS. 1B and 1C.

FIG. 6A shows a plan view of a modified pillow briquet 600 according to an embodiment of the invention. The briquet 600 has been modified by a Boolean difference operation. The volumes 612, each bounded by a dashed line and the outline of the modified briquet 600 indicate the volume that is missing from the pillow briquet 600 all the way from the face 610 shown in FIG. 6A and through the opposite face, which cannot be seen in FIG. 6A. The modified briquet 600 is the result of performing a difference operation on an unmodified pillow briquet. A shape as described in FIGS. 6C and 6D is subtracted from each of the four sides of the briquet 600. The shape that is subtracted is a straight cylinder with a cross section 613 as shown in FIG. 6C, and a transverse section 615, shown in FIG. 6D, as taken along the line D-D in FIG. 6C. The periphery 617 of briquet 600 is the same for face 610 as for the opposite face, which is not shown in FIG. 6A.

FIG. 6B shows a silhouette 620 of the briquet 600 as viewed from the side along either the B direction or the C direction in FIG. 6A. The silhouette 620 has the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. Thus, the modified briquet 600 has a pillow silhouette when viewed from at least one side.

The briquet 600 shown in FIGS. 6A and 6B has a nearly square periphery before modification and is symmetric about its midline as discussed above for the unmodified briquet 200 in FIGS. 2B and 2C. In other arrangements, the briquet 600 can have an round, elliptical, or nearly rectangular periphery before modification. In other arrangements, the briquet 600 can be asymmetric about its line of maximum width before modification, as discussed above for the unmodified briquet 100 in FIGS. 1B and 1C.

FIG. 7A shows a plan view of a modified pillow briquet 700 according to an embodiment of the invention. The briquet 700 has been modified by a Boolean difference operation. The modified briquet 700 is the result of performing a difference operation with a shape as described in FIGS. 7E and 7F in two approximately parallel places on an unmodified pillow briquet. The shape is a cylinder with a cross section 713 as shown in FIG. 7E and bent along its length so that is has a transverse section 715 as shown in FIG. 7F. The dotted regions 712 indicate a volume that is missing from the pillow briquet on the face 710 in view FIG. 7A.

In the example in FIG. 7A, the Boolean operation is performed on only one face, the face 710. FIG. 7B shows a silhouette 720 of the briquet 700 as viewed from the side along the B direction in FIG. 7A. The silhouette 720 has the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. Thus, the modified briquet 700 has a pillow silhouette when viewed from at least one side. FIG. 7C shows a silhouette 730 of the briquet 700 as viewed from the side along the C direction in FIG. 7A. The silhouette 730 does not have the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. In some arrangements, both faces of a briquet, such as the briquet 700, can be modified in the same way. In some arrangements, the Boolean operation performed on each face is the same. In other arrangements, the Boolean operation performed on each face is different. FIG. 7D shows a silhouette 740 of the briquet 700 for the case where the Boolean operation performed on face 710 and described above is performed on both faces of the briquet 700.

FIG. 8A shows a plan view of a modified pillow briquet 800 according to an embodiment of the invention. The briquet 800 has been modified by a Boolean difference operation. The dotted regions indicate a volume 812 that is missing from the pillow briquet on the face 810 shown in FIG. 8A. Each volume 812 has an outline 814 on the face 810 of the briquet 800. Each outline 814 is lenticular. The missing volumes 812 can be described as lenticular grooves. The modified briquet 800 is the result of performing a difference operation with a shape as described in FIGS. 8D and 8E on an unmodified pillow briquet. The shape is a disc 870 with a plan view 875 as shown in FIG. 8D. FIG. 8E shows a cross section 813 of the disc 870 as taken along any diameter. The cross section 813 has a lenticular shape. An example of a diameter is indicated by the dashed line 880 in FIG. 8D. The shape can also be described as an oblate spheroid 870 that has a plan view 875 as shown in FIG. 8D. The oblate spheroid 870 is a surface of revolution obtained by rotating an ellipse 813 as shown in FIG. 8E about its minor axis.

During the Boolean operation, only a portion of the disc or oblate spheroid 870 penetrates the pillow briquet 800. The maximum depth of intersection between the disc 870 and the briquet 800 can vary. The size of the portion of the oblate spheroid 870 can vary. FIGS. 8D and 8E show an example of a portion 887 of the disc or oblate spheroid 870 that can intersect with the pillow briquet 800. The portion 887 is bounded by edge 883 of the disc 870 and a plane through a chord such as a chord 885.

In the example in FIG. 8A, the Boolean operation is performed in two approximately parallel places on only one face, the face 810. FIG. 8B shows a silhouette 820 of the briquet 800 as viewed from the side along the B direction in FIG. 8A. The silhouette 820 has the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. Thus, the modified briquet 800 has a pillow silhouette when viewed from at least one side. FIG. 8C shows a silhouette 830 of the briquet 800 as viewed from the side along the C direction in FIG. 8A. The silhouette 820 does not have the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. In some arrangements, both faces of a briquet, such as the briquet 800, can be modified in the same way. In some arrangements, the Boolean operation performed on each face is the same. In other arrangements, the Boolean operation performed on each face is different.

FIG. 8F shows a cross section 845 of the pillow briquet 800 as cut along line F-F in FIG. 8A. The briquet 800 has a maximum thickness t. The regions 812 that are missing have a depth d as measured from the top of face 810. In some arrangements, the depth d is between about 0.15 and 0.25 times the thickness t. In other arrangements, the depth d is between about 0.18 and 0.22 times the thickness t.

In one embodiment, a charcoal briquet 900 is pillow shaped with an elliptical periphery when viewed from the top, as shown in the plan view in FIG. 9A. The briquet 900 has two grooves 912 in an upper surface 910 extending across the long dimension or major axis of the elliptical periphery. There are also two grooves in a lower surface, not visible in FIG. 9A. FIG. 9B shows a side view 940 of the briquet 900 as viewed along the B direction in FIG. 9A. FIG. 9C shows a side view 950 of the briquet 900 as viewed along the C direction in FIG. 9A. The briquet 900 has a convex upper surface, a convex lower surface, and is symmetrical with respect to a horizontal plane passing through its center. Thus, the bottom surface is also convex, and there are two parallel grooves in the bottom surface. The grooves can have a width about as wide as their maximum depth. In one arrangement, the grooves have a maximum depth that is about one fourth a maximum height of the briquet. In some arrangements, there can be more than two grooves in one of or both the upper surface and the lower surface. In one arrangement, there are three parallel grooves in both the upper surface and the lower surface. In some arrangements, the grooves can be parallel to the short dimension or minor axis of the elliptical periphery.

FIG. 10A shows a plan view of a modified pillow briquet 1000 according to an embodiment of the invention. The briquet 1000 has been modified by a Boolean union operation. The cross-hatched areas indicate a volume 1012 that has been added to a pillow briquet on a face 1010 shown in FIG. 10A. The modified briquet 1000 is the result of performing a union operation with a shape as described in FIGS. 10C and 10D in four places on an unmodified pillow briquet. The shape is an ovoid with a cross section 1011 as shown in FIG. 10C and a transverse section 1013 as shown in FIG. 10D. In the example shown in FIG. 10A, only about half the ovoid intersects with the briquet in each of the four union operations, leaving about half the ovoid to protrude from the face 1010.

In the example in FIG. 10A, the Boolean operation is performed on only one face, the face 1010. FIG. 10B shows a silhouette 1020 of the briquet 1000 as viewed from the side along either the B or C directions in FIG. 10A. The silhouette 1020 has the same shape as the silhouette 220 of the unmodified pillow briquet 200 shown in FIG. 2D. Thus, the modified briquet 1000 has a pillow silhouette when viewed from at least one side. In some arrangements, both faces of a briquet, such as the briquet 800, can be modified in the same way. In some arrangements, the Boolean operation performed on each face is the same. In other arrangements, the Boolean operation performed on each face is different.

The foregoing embodiments are meant to serve as examples of possible briquet shapes that can result from performing Boolean operations on pillow briquets. Embodiments of the invention are not limited to these examples alone.

In some embodiments, the packing density of the briquets modified by Boolean operations is less than the packing density of the unmodified briquets. In some arrangements, the packing density for modified pillow briquets is between about 0.70 and 0.92 times the packing density for unmodified pillow briquets having about the same dimensions. In other arrangements, the packing density for modified pillow briquets is between about 0.80 and 0.88 times the packing density for unmodified pillow briquets having about the same dimensions. As discussed above, the packing density for unmodified briquets is about 50%. In some arrangements, the packing density for modified pillow briquets is between about 35% and 46%. In other arrangements, the packing density for modified pillow briquets is between about 40% and 44%.

The briquets as described in the embodiments herein and their reduced packing density have several advantages including weight advantages, ease of use, environmental and manufacturing advantages over ordinary pillow shaped briquets.

Reduced packing density results in several consumer advantages. Generally consumers decide how much charcoal to use for a particular cooking task based on volume, not weight. Consumers do not weigh briquets to determine the amount to use. Instead, they pour out an amount of briquets to make a pile of a certain size or to fill a chimney to a certain level. They judge the amount to use based on a randomly packed volume. It takes approximately the same number of modified briquets as unmodified briquets to fill the same randomly packed volume. Consumers consider the size of the grill and whether the amount of food they are cooking will cover the grill surface completely or only partially. Consumers want to have a sufficient number of burning briquets so that when they spread out, the briquets will provide an amount of cooking area sufficient for the task. The same number of briquets, either modified or unmodified, are sufficient for the task in most cases.

A bag of modified briquets that has about the same volume as a bag of unmodified briquets contains about the same number of briquets but weighs less. It is easier for a consumer to lift and carry a bag of modified briquets than a bag of unmodified briquets. It is easier to lift the bag and pour the briquets out into the grill. Yet, a consumer can use either bag of briquets to perform about the same number of cooking tasks.

Modified pillow briquets have environmental advantages. Typically when consumers finish a cooking task, there is still a lot of burn time left in the briquets. After cooking is finished, briquets continue to burn until the charcoal has all turned to ash. In many cases, the cooking time is very small compared to the total burning time of the briquets. As discussed above, consumers tend to determine the amount of charcoal briquets to use for a cooking task based on the randomly packed volume, not on the weight of the charcoal. For a given randomly packed volume of briquets, that is, a given number of briquets, the total burn time is less for modified briquets than for unmodified briquets because the total amount of charcoal is less. Cooking time constitutes a larger portion of the total burn time for modified briquets than for unmodified briquets. A larger portion of the total burn time is used in cooking for the modified briquets than for the unmodified briquets. Thus the burn time is used more efficiently for the modified briquets than for the unmodified briquets. For the same cooking task, less total charcoal weight is burned for the modified briquets than for the unmodified briquets. Less charcoal burned means a smaller amount of bum byproducts released into the air and less residual ash to remove.

The modified briquet can light more quickly and have a shorter ignition phase than the unmodified briquet. This can result in needing less lighter fluid to light the briquets and therefore a smaller amount of lighter fluid byproducts released into the air.

Modified briquets have manufacturing advantages. Less raw material is used to make the same number of modified briquets as compared to unmodified briquets. A modified briquet contains less actual material weight than an unmodified briquet so there can be less wear per briquet on the press rolls used to form the briquets. Less material per modified briquet can also mean that the raw briquets take less time to dry. As drying is often the limiting step in briquet manufacturing throughput, quicker drying can mean faster throughput in the manufacturing process. The advantages in faster throughput are many. This can result in greater output per factory, thus yielding a better return on large capital investment. This can result in greater overall efficiencies in labor and associated costs.

In many cases, the cost of transportation can be directly related to the weight transported. There are transportation cost advantages with modified briquets. These advantages start with transportation of raw materials. Less raw material is used to make modified briquets than to make unmodified briquets. The transportation costs associated with a given amount of raw material will be spread over production of more modified briquets than unmodified briquets. The cost savings continues with transportation of finished briquets. It takes about the same number of bags of modified briquets as unmodified briquets to fill a truck to its maximum volume. But a truck full of modified briquets weighs less than a truck full of unmodified briquets. Less weight means the truck uses less fuel per unit distance to transport the modified briquets than to transport the unmodified briquets. In many cases, trucks loaded with unmodified briquets reach their maximum weight limit before they reach their volume limit, so partially empty trucks are used to transport unmodified briquets. When modified briquets are loaded, more bags of briquets can be loaded before the truck reaches its maximum weight limit. This reduces the cost of transportation per bag by requiring fewer trucks overall to transport the same number of bags of briquets.

EXAMPLE

An unmodified pillow briquet 200 having a shape approximately as shown in FIGS. 2A-2D was made using standard manufacturing practices. FIG. 2A shows a plan view of the briquet 200. FIG. 2D is a silhouette of the briquet 200 as viewed along either direction B or direction C in FIG. 2A. A modified pillow briquet 800 having a shape approximately as shown in FIGS. 8A-8C was made using standard manufacturing practices. FIG. 8A shows a plan view of the briquet 800. FIG. 8B is a silhouette of the briquet 800 as viewed along direction B in FIG. 8A. FIG. 8C is a silhouette of the briquet 800 as viewed along direction C in FIG. 8A.

Random packing mass density measurements were made by pouring as many briquets as could fit into a container having a known volume and weight. The weight of the container filled with briquets was measured for the unmodified pillow briquets and for the modified pillow briquets. The random packing mass density was found by dividing the weight of the briquets (total weight minus the weight of the container) by the volume of the container. The random packing mass densities are shown in Table I. The glass bead densities, that is, the densities of the finished material, were the same for each kind of briquet. Normalized random packing mass density was determined by dividing random packing mass density by the glass bead density and multiplying by 100%.

The random packing density of the unmodified pillow briquets was nearly 50%. The random packing density for the modified pillow briquets was only 43.6%. There was a nearly 12% reduction in the packing density of the modified pillow briquets. TABLE I Random Packing Glass Bead Random Packing Mass Density Density Density (grams/cm³) (grams/cm³) (normalized) Unmodified 0.405 0.82 49.4% Pillow Briquets Modified 0.357 0.82 43.6% Pillow Briquets

This invention has been described herein in considerable detail to provide those skilled in the art with information relevant to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by different equipment, materials and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself. 

1. A modified charcoal briquet comprising: a pillow shaped charcoal briquet modified by Boolean geometric operations to yield a random packing density between about 35% and 46%; wherein the modified charcoal briquet comprises less volume than a pillow shaped charcoal briquet unmodified by Boolean geometric operations and having the same dimensions; wherein the random packing density for the modified charcoal briquet comprises about 0.70 times and 0.92 times the random packing density for the unmodified charcoal briquet.
 2. The modified charcoal briquet of claim 1 wherein the random packing density for the modified charcoal briquet is between about 0.80 times and 0.88 times the random packing density for the unmodified pillow briquet.
 3. The modified charcoal briquet of claim 1 wherein the random packing density for the modified charcoal briquet is between about 40% and 44%.
 4. The modified charcoal briquet of claim 1 wherein the modified charcoal briquet comprises a first silhouette when viewed from at least one side that is identical to a second silhouette when viewed from at least one side of the unmodified charcoal briquet.
 5. The modified charcoal briquet of claim 1 further comprising at least one lenticular groove on at least one face of the modified charcoal briquet; wherein the lenticular groove is approximately parallel to an edge of the modified briquet.
 6. The modified charcoal briquet of claim 5 wherein the groove does not intersect with an edge of the modified briquet.
 7. The modified charcoal briquet of claim 5 wherein the groove has a maximum depth and a maximum thickness, and the maximum depth is between about 0.15 and 0.25 times the maximum thickness.
 8. The modified charcoal briquet of claim 7 wherein the maximum depth is between about 0.18 and 0.22 times the maximum thickness.
 9. The modified charcoal briquet of claim 1 further comprising at least two lenticular grooves on at least one face of the modified briquet; wherein the lenticular grooves are approximately parallel to an edge of the modified briquet.
 10. The modified charcoal briquet of claim 9 wherein the grooves do not intersect with an edge of the modified briquet.
 11. The modified charcoal briquet of claim 9 wherein the groove has a maximum depth and a maximum thickness, and the maximum depth is between about 0.15 and 0.25 times the maximum thickness.
 12. The modified charcoal briquet of claim 11 wherein the maximum depth is between about 0.18 and 0.22 times the maximum thickness. 